Phyletic gradualism is a model of
evolution which theorizes that most
speciation is slow, uniform and gradual. When evolution occurs in this mode, it is usually by the steady transformation of a whole
species into a new one (through a process called
anagenesis). In this view no clear line of demarcation exists between an ancestral species and a descendant species, unless
splitting occurs. The theory is contrasted with
punctuated equilibrium.